“The neighbours had mentioned a bunker but I hadn’t thought anymore about it.

“I was talking to the builder about it while we were having a cup of tea in the garden and he said, ‘Come on let’s have a look!”

The first cavity, which had a metal ladder about 8ft to 10ft in length attached, was full of water so they spent two days pumping it out.

At the bottom of the ladder was a wooden door which was open and led to the two rooms in solid concrete. The first measures about four metres by three metres and the second about five metres by three metres.

At the end of that room, the pair found another door. Tony dug out the rubble behind the door and discovered another ladder.

“It’s an emergency escape ladder in case the first one was destroyed or blocked by rubble from a bomb,” said Chris.